Polycarbonates



United States Patent 3,414,542 POLYCARBONATES John Vitrone,Parsippany-Troy Hills Township, Morris County, NJ., assignor to AlliedChemical Corporation, New York, N.Y., a corporation of New York NoDrawing. Original application Sept. 25, 1961, Ser. N0. 140,220, newPatent No. 3,232,993, dated Feb. 1, 1966. Divided and this applicationJuly 12, 1965, Ser. No.

4 Claims. (Cl. 260-47) ABSTRACT OF THE DISCLOSURE Polycarbonates areformed by the reaction of phosgene with halogenated bisphenols of theformula:

wherein R is a member of the group consisting of hydrogen and alkylradicals, preferably lower alkyl radicals (i.e., containing from 1 to 4carbon atoms), X is a halogen, n is an integer from 0 to 4 and m: is aninteger from 1 to 4. X may be the same or different halogens, but, ineach case, is preferably chlorine. These polycarbonates are flameresistant and have high glass transition and fusion temperatures. Theymay be molded into tough, clear and nonfiammable films.

This application is a division of application Ser. No. 140,220, filedSept. 25, 1961, now U.S. Patent No. 3,232,- 993, issued Feb. 1, 1966.

This invention relates a new group of halogenated bisphenols and totheir preparation.

The halogenated bisphenols of this invention may be represented by thefollowing general formula:

in which R is a member of the group consisting of hydrogen and alkylradicals, preferably lower alkyl radicals (i.e., containing from 1 to 4carbon atoms), X is a halogen, n is an integer from 0 to 4 and m is aninteger from 1 to 4. X may be the same or different halogens, but, ineach case, is preferably chlorine. The following halogenated bisphenolsare illustrative of those within the scope of this invention:

conventionally, bisphenols are prepared by the condensation of phenolswith carbonyl compounds in the pres- Patented Dec. 3, 1968 ence of amineral acid catalyst. Although these methods have been heretoforesuccessfully employed, it has been discovered that they are notapplicable for the preparation of the halogenated bisphenols of thisinvention.

According to the present invention, a halogenated bisphenol is producedby reacting an u,a-di-halo-p-xylene compound having the followinggeneral formula:

in which X is a halogen (preferably chlorine), Y is a halogen(preferably chlorine) and m is an integer from 1 to 4, with at least astoichiometric amount of a phenolic compound having the followinggeneral formula:

in which R is a member of the group consisting of hydrogen and alkylradicals (preferably lower alkyl radicals), X is a halogen (preferablychlorine) and n is an integer from 0 to 4, at temperature of about to C.in the presence of an anhydrous acid-activated clay as catalyst andrecovering the halogenated bisphenol from the resulting reaction mass.The reaction which takes place may be represented by the followingequation:

I Xn Xm 2HO YCH2"CH2Y Xn Xm Xn III H H H Rn Rn X and Y may be the sameor different halogens but, as indicated above, each is preferablychlorine.

Among the suitable halogenated xylene reactants are:

oz, n',2-trichloro-p-xylene a,u,dichloro-2-bromo-p-xylene a,x',2,3-tetrachloro-p-xylene a,u,dichloro-2,3-difluoro-p-xyleneu,a',dichloro-2,6-dibromo-p-xylene (Z,0L',2,3 ,5 ,6-hexachloro-p-xylenea,u,dichloro-2,3,5,6-tetrabromo-p-xylene Among the suitable phenolicreactants are:

phenol 2-chlorophenol 2-methylphenol 2,6-dimethylphenol2-chloro-6-methylphenol Although the reaction may be carried out usingstoichiometric quantities of the halogenated xylene compound andphenolic compound, it has been discovered that greater efficiency andhigher yields of product are obtained when about 4 to 10 mols ofphenolic compound per mol of the halogenated xylene are employed.

Generally speaking, an acid-activated clay consisting mainly of silicaand alumina is used as catalyst in the process of this invention.Preferably, the catalyst comprises an acid-activated clay of thenon-swellable, bentonite-type. This type of clay contains about 40 to 65percent by weight of silica and about 3 to 20 percent by weight ofalumina, as well as small quantities of one or more oxides of othermetals such as iron, magnesium, sodium, calcium and potassium.

The water content of the acid-activated clay negatively affects itsactivity as catalyst. Hence, the clay must be employed in anhydrousform. This may be effectively accomplished by treating the clay, eitherbefore or after its addition, with a suitable low-boiling solvent, suchas benzene, toluene, cyclohexane, etc., and then distilling off thewater in the form of an azeotrope with the solvent.

If the clay on hand is not acid-activated, it may be activated by anysuitable procedure. For example, a slurry of one part by weight of clayto 10 parts by weight of 5 percent sulfuric acid solution may be boiledfor a period of one hour. The excess spent acid may then be separatedfrom the clay first by settling and decantation and then by wringing thewet clay. The mud thus produced may then be dried to a powder in a flashdrier.

Generally speaking, an amount of acid-activated clay equivalent to about5 to 30 percent by weight of the phenol reactant is employed, about 8 to12 percent by weight being preferred.

The reaction may be carried out at temperature within the range of about80 to 180 C.; however, particularly outstanding results are obtainedwhen the reaction temperature is maintained within the range of about140 to 180 C. Although the time of reaction may be as little as about1.5 hours, completion of the reaction generally requires at least about3 to 6 hours.

The halogenated bisphenols may be recovered from the reaction mass byany convenient means. For example, the reaction mass may be filtered toremove the clay, and unreacted phenolic compound extracted from the masswith hot water. The crude product may then be purified by means wellknown in the art, as by recrystallization from a suitable solvent suchas methyl alcohol, isopropyl alcohol, dioxane or dimethylformamide.

In preferred operation, the halogenated xylene and phenolic reactantsare mixed, and an acid-activated clay in anhydrous form is added to themixture. The reaction mixture is then heated at temperature of about 140to 180 C. for a period 3 to 6 hours. The resulting reaction mass isfiltered to remove the clay, and unreacted phenolic compound isextracted with hot water. The crude product is then recrystallized froma suitable solvent as described above.

The following examples are given for the purpose of illustrating thepresent invention but are not intended to be limiting on the scopethereof. In the examples, parts are by weight.

Example 1 940 parts of phenol and 159.5 parts ofa,a',2,3,5,6h6Xachloro-p-xylene were mixed and heated to temperature ofabout 60 C. 50 parts of an acid-activated, bentonite clay (containingabout 64 percent by weight of silica, about 17 percent by weight ofalumina and also small amounts of iron oxide, magnesium oxide andcalcium oxide) were added. About 90 parts of benzene were introducedinto the reaction mixture, and water present in the clay was removed byazeotropic distillation. The remaining benzene was then distilled off,and the reaction temperature was maintained at 160 C. for a period of 6hours.

The resulting reaction mass was filtered to remove the clay, andunreacted phenol was extracted with hot water. The crude product wasthen crystallized three times from 80 percent aqueous methyl alcohol andonce from anhydrous isopropyl alcohol. A white crystalline material,comprising substantially pure 1,4-bis(p-hydroxybenzyl)2,3,5,6-tetrachlorobenzene having a melting point of about 262 to 264 C.with slight decomposition, was produced. Elemental analysis of theproduct gave 56.24 percent carbon and 3.5 percent hydrogen (theory-56.08percent carbon and 3.3 percent hydrogen).

940 parts of phenol and 396 parts of a,a',2,3,5,6-hexachloro-p-xylenewere mixed and treated with parts of the acid-activated clay employed inExample 1. 86.6 parts of toluene were added to the reaction mixture, andthe water present in the clay was removed by azeotropic distillation for1 hour at about to C. Upon completing dehydration of the clay, thereaction commenced and proceeded for 3.5 hours at C.

The resulting reaction mass was cooled to 80 C., and the clay catalystwas filtered off. Unreacted phenol was removed by extraction with hotwater. After 3 recrystallizations from isopropanol, a white crystallinematerial, comprising substantially pure 1,4-bis(p-hydroxybenzyl)2,3,5,6-tetrachlorobenzene, was produced.

Example 3 240 parts of 2,6-dimethylphenol were mixed with 62 parts ofx,a,2,3,5,6-hexachloro-p-xylene. 50 parts of the acid-activated clayemployed in Example 1 were added, followed by about 86.6 parts oftoluene. The reaction mixture was heated in order to remove the waterpresent in the clay by azeotropic distillation. The reaction temperaturewas then elevated to about 140 to 150 C. and maintained there for aperiod of 1 hour.

The resulting reaction mass was cooled to about 80 C. and filtered. Thesolid residue containing the clay catalyst and the crude product wasfirst washed with toluene and then treated with hot dioxane whichdissolved the product. The clay was filtered ofr, and the crude productcrystallized out on cooling. The product was then recrystallized fromdioxane and dimethylformamide to produce1,4-bis(4-hydroxy-3,S-dimethylbenzyl) 2,3,5,6-tetrachlorobenzene havinga melting point of 310 to 313 C. with slight decomposition. Elementalanalysis of the product gave 60.0 percent carbon, 4.97 percent hydrogenand 29.3 percent chlorine, as compared to the theoretical values of 59.5percent carbon, 4.5 percent hydrogen and 29.3 percent chlorine.Titration of the phenolic hydroxy groups gave 7.18 percent as aganistthe theoretical value of 7.02 percent.

The halogenated bisphenols of this invention are useful in thepreparation of more complex organic derivatives, includingpolycarbonates and epoxy resins. When, for example, the sodium salt of1,4-bis(p-hydroxybenzyl) 2,3,5,6-tetrachlorobenzene is reacted withphosgene, a polycarbonate is produced. An epoxy resin is formed whenl,4-bis(phydroxybenzyl) 2,3,5,6-tetrachlorobenzone is reacted withepichlorohydrin in an alkaline medium.

In a typical example for making a polycarbonate, phosgenation of aslurry of the sodium salt of 1,4-bis (phydroxybenzyl)2,3,5,6-tetrachlorobenzene in an aqueous sodium hydroxide-ethylenechloride interfacial system gave a high yield (82 percent of theory) ofethylene chloride-insoluble crystalline polymer having an inherentviscosity of 0.2 to 0.3 in symmetrical tetrachloroethane. The polymerhad a glass transition temperature of about C., a fusion temperature ofabout 290 C. and was flame-resistant. A tough, clear and non-flammablefilm was compression molded from the polymer at 300 C.

While the preferred embodiments for carrying out this invention havebeen described, it will be apparent that many changes may be madetherein Without departing from the spirit of the invention.

I claim:

1. A polycarbonate consisting essentially of recurring units of thestructure:

wherein R is a hydrogen or alkyl radical, X is a halogen, n is aninteger from 0 to 4 and n is an integer from 0 to 6 the sum of n and nbeing less than 5, and m is an integer wherein n and n are both 0, saidpolycarbonate having a from 1 to 4. glass transition temperature ofabout '170" C.

2. A polycarbonate consisting essentially of recurring 4. A tough, clearand nonflannnable molded film conunits of the structure: sistingessentially of the polymer of claim 3.

5 Xu H C1 I H Km 0 References Cited o b o ll UNITED STATES PATENTS I 1 1(5 1'1 1 3,028,365 4/1962 Schnell et a1. 260-47 R11 1 3,094,508 6/1963Butterworth et al. 260 47 wherein R is a hydrogen or alkyl radical, X isa halogen, 10 3,248,365 4/ 1966 Oxenrider et al. 26047 n is an integerfrom O to 4 and n is an integer from 0 to 3,251,805 5/ 1966 Schnell etal. 260-47 4, the sum of n and n' being less than 5.

3. A polycarbonate in accordance with claim 2, SAMUEL H. BLECH, PrimaryExaminer.

